Source-1-Games [Portal, HL2] SSSE3 SIGILL when trying to run either game

System information: https://gist.github.com/xrogaan/381d98f0ad48b6be99b00d0b3cdb2646

After the recent update for the steam deck, I became unable to run either game. Apparently, they now require a SSSE3 capable CPU.

Running with gdb gives the backtrace:

Thread 1 "hl2_linux" received signal SIGILL, Illegal instruction.
0xe5d8566e in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/engine.so
(gdb) bt
#0  0xe5d8566e in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/engine.so
#1  0xe5d3ec47 in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/engine.so
#2  0xf7fe304c in ?? () from /lib/ld-linux.so.2
#3  0xf7fe3152 in ?? () from /lib/ld-linux.so.2
#4  0xf7fe6457 in ?? () from /lib/ld-linux.so.2
#5  0xf7ea4614 in _dl_catch_exception () from /lib/i386-linux-gnu/libc.so.6
#6  0xf7fe6f1b in ?? () from /lib/ld-linux.so.2
#7  0xf7ea45b9 in _dl_catch_exception () from /lib/i386-linux-gnu/libc.so.6
#8  0xf7fe6796 in ?? () from /lib/ld-linux.so.2
#9  0xf7f4f2c8 in ?? () from /lib/i386-linux-gnu/libdl.so.2
#10 0xf7ea45b9 in _dl_catch_exception () from /lib/i386-linux-gnu/libc.so.6
#11 0xf7ea4680 in _dl_catch_error () from /lib/i386-linux-gnu/libc.so.6
#12 0xf7f4fb11 in ?? () from /lib/i386-linux-gnu/libdl.so.2
#13 0xf7f4f364 in dlopen () from /lib/i386-linux-gnu/libdl.so.2
#14 0xf608161b in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/filesystem_stdio.so
#15 0xf60817c2 in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/filesystem_stdio.so
#16 0xf60434f2 in ?? () from /mnt/Games/usr/xrogaan/SteamLibrary/steamapps/common/Portal/bin/filesystem_stdio.so
#17 0xf7d11a6a in ?? () from bin/launcher.so
#18 0xf7d127a3 in ?? () from bin/launcher.so
#19 0xf7d12b0d in ?? () from bin/launcher.so
#20 0xf7cf5c65 in ?? () from bin/launcher.so
#21 0xf7d12466 in ?? () from bin/launcher.so
#22 0xf7d126b2 in ?? () from bin/launcher.so
#23 0xf7d14a2b in ?? () from bin/launcher.so
#24 0xf7d126c4 in ?? () from bin/launcher.so
#25 0xf7cf77c6 in LauncherMain () from bin/launcher.so
#26 0x565555b7 in main ()

layout asm points to the following instruction : >0xe5d8566e pshufb %xmm4,%xmm7

Dump file, if necessary: assert_20220322013214_34.dmp.tar.gz

Mar 22 '22 00:03 xrogaan

I got this issue after installing the game with a fairly recent Intel CPU, then booting the system with an older AMD CPU.

The engine.so file that contains the illegal instruction is exactly identical between systems where it works on and systems where it doesn't, so that points to some config file... unless it's some feature that's supported on more recent AMD and Intel CPUs while missing on older AMD CPUs.